DocBook is a DTD maintained by the DocBook Technical Committee of
OASIS. It is particularly well suited to books and papers about
computer hardware and software (though it is by no means limited
to these applications).

Because it is a large and robust DTD, and because its main structures
correspond to the general notion of what constitutes a "book",
DocBook has been adopted by a large and growing community of authors
writing books of all kinds.

DocBook is supported "out of the box" by a number of commercial
tools, and there is rapidly expanding support for it in a number
of free software environments.

This ports installs all versions of the DocBook SGML DTD from 
versions 3.x and 4.x, and the last major release on the 2.x branch.
The XML versions include the latest one, and a few other commonly
used revisions.

If you are creating a new document, always try to use the latest 
version of the DTD.

There is a free online copy of O'Reilly's definitive guide to DocBook
available at http://www.docbook.org/tdg/html/docbook.html
